Stinging cells embedded into the tentacles of cnidarians that contain tiny harpoons are called

The stinging cells embedded into the tentacles of cnidarians that contain tiny harpoons are called nematocysts.

Nematocysts are specialized organelles found in the cnidocytes, which are the stinging cells of cnidarians such as jellyfish, sea anemones, and corals. Each nematocyst is composed of a capsule that contains a coiled, thread-like structure. When an appropriate stimulus, such as contact with a potential prey or threat, triggers the cnidocyte, the nematocyst explosively evert, swinging the stinging thread outward. This thread can penetrate the skin of the creature, delivering toxins that can paralyze or kill prey and deter predators.

Nematocysts are crucial for the survival of cnidarians, aiding in both offense and defense, as their stings can be potent and effective in incapacitating other marine organisms.